Portable AC power source?

[Michael Torrie]

Charles Curley wrote:
>> Anyone know of a good PORTABLE AC power source? Something like a UPS
>> or something, but smaller. It doesn't have to be big, just enough to
>> power a couple of external devices to my laptop.
> 
> Simplest solution: an inverter. Get one specifically designed for solid
> state electronics, e.g. laptops, etc. It must produce a sine wave, and
> if the salesman doesn't know what a sine wave it, it doesn't. For what
> you are doing, a 140 watt inverter is fine. My Lenovo R51 is rated for
> 70 watts and actually draws around 40.

Of course converting DC to AC back to DC is convenient, but not
efficient.  If his portable hard drive is 12 V (many are these days),
then maybe he could run it directly off his car electrics with a regulator.

I've used el-cheapo inverters for years (probably square wave instead of
a nice sine) and they seem to work fine, although they induce some noise
in my computer's audio.  A ferrite choke helps that though.